Four leading supermarkets have all announced a cut in their petrol and diesel prices ahead of the bank holiday weekend.
Morrisons led the way by cutting the price of its petrol by up to 2p a litre and diesel by 1p a litre.
Sainsbury's then announced it would be cutting its petrol and diesel prices by up to 2p a litre from Friday.
Then Asda and Tesco made announcements. Asda said that from Friday morning drivers filling up at any of its 217 forecourts nationwide would pay no more than 129.7p a litre for petrol and 134.7p a litre for diesel.
Tesco said it would be reducing its petrol and diesel prices at its 497 forecourts by up to 2p a litre.
AA public affairs head Paul Watters said: "Today's supermarket price war comes on the back of yesterday's 40-dollars-a-tonne fall in petrol wholesale prices across Europe - equivalent, with VAT, to a 2.5p-a-litre fall at the pump. However, just as one swallow doesn't make a summer, two days of commodity price falls doesn't signal the end of drivers' pump misery.
"If this trend continues, that would be a good start to the summer season but no-one should under-estimate the market's ability to send prices shooting up again, often just on pure speculation."
Mr Watters said that on Wednesday the average UK price of petrol fell to 134.77p a litre and diesel to 139.24p. This compared with start-of-the-year prices of around 132p for petrol and 140p for diesel.
He added: "However, in parts of London, non-supermarket petrol can be bought for as little as 129p a litre. Even so, the fact that petrol this time three years ago was 121.42p puts current fuel costs in stark contrast."
RAC technical director David Bizley said: "With thousands taking to the roads for this first bank holiday weekend of the summer, it's great to see the supermarket fuel price-cutting trend of recent weeks continuing. It only seems fair that motorists should benefit from the reduction in wholesale fuel prices."